Fast Action Roundup Ready to Use Weedkiller is a systemic weedkiller that kills weeds from the inside out. Fast Action Roundup attacks the roots to stop weeds returning. The fast acting formula gives results in 1 - 2 days. It also fully degrades in soil to allow replanting. Use Fast Action Roundup Ready to Use Weedkiller 1L from February to November. Fast Action Roundup Ready to Use Weedkiller 1L will treat up to 30m